In making various parts, it is necessary to deburr and polish the parts for final finishing such as plating and the like.
In one type of finishing machine that has been used, a vertical tub was positioned in a stationary support and parts were mounted on a fixture that was rotated about a vertical axis in damp powdered abrasive material in the tub.
In another type of machine, a large round drum was positioned horizontally and driven at high speed. The parts were conveyed into the drum by a fixtures on a conveyor. As the parts entered the drum, cams on the conveyor structure moved the workpieces into the abrasive media in the drum.
In another type of machine, the parts were mounted on fixtures, each fixture holding one piece which was slowly revolved in the abrasive media of a rotating drum.
In U.S. Pat. No. 2,899,777, a rotating head supports counter rotating vertical spindles on which the parts were mounted so that they were spun through the loose abrasive compound in a stationary tub.
In a further type of finishing apparatus, the parts are supported on a work carrier and positioned such that as a drum containing the abrasive media is rotated, the parts are subjected to the abrasive action of the compound. The carrier is provided with an indexing mechanism for moving the part to orient it with respect to the drum.
In connection with machines that have been used where the drum is rotated at high speed causing the abrasive media to collect about the side wall of the drum, it has been common to utilize a rack positioned so that it will periodically loosen and mix the media. Such an arrangement does not furnish completely effective mixing of the compound.
Among the objectives of the present invention are to provide a method and apparatus which will result in a rapid cutting and finishing action, wherein the abrasive media or compound is mixed thoroughly and will not become compacted and which can be readily adapted to different shapes and sizes of parts and different materials of parts.
In accordance with the invention, a finishing method and apparatus wherein a tub containing loose abrasive material is rotated at high speeds about a vertical axis to cause finishing media to form a layer of media along the side wall of the tube. One or more workpieces to be finished are supported in the media and are rotated about a vertical axis coincident or parallel to the axis of the tub such that a rapid cutting and finishing action is provided by the relative movement of the tub and the workpieces. The method and apparatus further comprises removing compound continuously from the lower part of the tub and cooling the material and returning it to the tub.